The present invention relates to an input device that detects capacitance that changes depending on the pressing state of a movable electrode, and outputs an input signal.
A capacitance force sensor that detects the amount of change in capacitance that differs depending on the pressing force and the pressing direction of an operation section, and outputs at least one of an X-axis input signal, a Y-axis input signal, and a Z-axis input signal, has been known as an input device used for electronic instruments and the like.
For example, JP-A-11-132872 discloses a capacitance input detection device in which electrodes Dx+, Dx−, Dy+, Dy−, and the like are disposed on a substrate, the electrodes being coated with a resist film, and a dome-shaped metal plate and an operation button being disposed over the electrodes. When employing such a structure, however, the number of parts and the production cost increase. Moreover, since the size of the entire device necessarily increases, it is difficult to reduce the thickness and the size of the device.
Since it is necessary to provide a housing that holds the dome-shaped metal plate and the operation button, it is difficult to secure the input device on an irregular surface of an electronic instrument due to poor flexibility.
Since such an input device is configured so that a change in capacitance is nonlinear with respect to the force applied to the operation button, a comfortable operation feel cannot be obtained when the output is not adjusted using software or the like. This may make it necessary to use an expensive CPU depending on the adjustment load, so that an increase in cost may occur.